1. Field of the Invention
The present invention relates to communication systems, and in particular to a step of deciding how to control communications via a gateway. The decision may relate to control operations such as authorization and policy control applied to communications routed via a gateway.
2. Description of the Related Art
A communication system can be seen as a facility that enables communication between two or more entities such as user equipment, servers, gateways and/or other nodes. The communication may comprise, for example, communication of voice, data, multimedia and so on. A communication system may enable a user thereof to be provided with various types of services. For example, a user equipment may be in communication with an application server (AS), such as a service provider server, via a communication system.
The term “service” used above and hereinafter will generally be understood to broadly cover any service which a user may desire, require or be provided with by means of the communication system. The term also will generally be understood to cover the provision of complimentary services. In particular, but not exclusively, the term “service” will be understood to include browsing, downloading, email, streaming services, Internet Protocol multimedia (IM) services (IMS), conferencing, telephony, gaming, rich call, presence, e-commerce and messaging, for example, instant messaging.
Signalling between various entities associated with a communication session is typically required in order to control the communication session. Control is typically required for the set-up of the communication session and also later on during communication on the established session. The signalling can be based on an appropriate communication protocol or protocols.
The communication may be provided by fixed line and/or wireless communication interfaces. An example of the fixed line system is a public switched telephone network (PSTN). The wireless communication may be provided by means of a mobile communication system. Another example of the wireless communication systems is the Wireless Local Area Network (WLAN). Mobile communications systems refer generally to any telecommunications systems which enable a wireless communication for users who may move within the service area of the system. An example of a typical mobile communications systems is a Public Land Mobile Network (PLMN).
A wireless communications system is typically provided with a plurality of access networks. The access networks are for providing a user with a wireless access to the core network part of the communication network. An access network typically comprises at least one base station system and a radio network controller functionality. The access network may be configured to provide a packet service for mobile user equipment via the base stations.
The mobile communication network may then be used for access to other destinations, such as other networks, hosts, services offered by specific service providers and so on. Such an access is provided by nodes commonly referred to as access points. Typically an access point or gateway node of the mobile communication network provides further access to an external network or an external host. For example, if the requested service is provided by a service provider located in another network, the service request is routed via a gateway to the other network and the service provider. The routing may be based on definitions in the mobile subscriber data stored in the mobile network.
A user may need to be a subscriber to the communications system in order to be able to use services provided by means of the communication system. Subscriber data is typically stored in a subscriber database for each subscriber. The database is commonly controlled by the operator of the networks providing the access service. The subscriber data may comprise information regarding the quality of service (QoS) the subscriber is entitled to receive, priorities, service restrictions, security, authentications, charging and so on.
Various different communication standards and protocols have already been developed. New standards and protocols are also continuously developed. To distinguish the earlier developments from the more recent developments, the mobile communication standards are divided in different generations. For example, some standards, such as the first digital cellular standards, are referred to as the second generation (2G) standards while the more recent developments of the digital mobile telephony are often referred to as the third generation (3G) standards.
The access networks the user may use to access services may support substantially different features, depending on the standard used and/or the generation/version of the standard. Furthermore, user may use access networks that are based on unlicensed radio or fixed access techniques. Such access techniques may support substantially different features, depending on the standard, and the manner the individual access systems are built and how these access system are connected to a backbone network. It shall be appreciated that unlike the well standardised cellular mobile systems, there are no strict and/or commonly accepted standards for the unlicensed access systems. For example, public Wireless Local Area Networks (WLAN), residential WLAN, and enterprise WLAN can each be technically considered as being a different access network type. Also, public WLAN access networks for different types of hotspots may be considered as different access network types. For example, different type of WLAN access networks may be provided in hotels in general than in a specific hotel or hotel chain, and so on.
A more detailed example of the possible problems that may be caused by differences between access network types is described below with reference to the general packet radio service (GPRS).
A GPRS based communication system is an example of wireless communication systems that provide packet-switched data transmission for a mobile user equipment. The GPRS operational environment comprises one or more service areas, which are interconnected by a GPRS backbone network. A service area may comprise a number of packet data service nodes (SN). In this specification the service nodes will be referred to as serving GPRS support nodes (SGSN). Each of the SGSNs is connected to at least one radio access network. The access networks may be either 2G or 3G access networks.
The packet data serving nodes are in turn connected to an external data network, e.g. to a public switched data network (PSPDN), via appropriate gateways, such as GPRS gateway support nodes (GGSN). The GPRS thus allow transmission of packet data between mobile user equipment and external data networks.
An example of the data bearers that may be used to carry the traffic flows over the GPRS is a packet data protocol (PDP) context. A PDP context typically includes a radio access bearer provided between the user equipment, the radio network controller and the SGSN, and switched packet data channels provided between the serving GPRS service node (SGSN) and the gateway GPRS service node (GGSN). A session between the user equipment and other party would then be carried on the established PDP context. A PDP context can carry more than one traffic flow, but all traffic flows within one particular PDP context are treated in the prior art the same way as regards their transmission across the network. The requirement regarding similar treatment is based on PDP context treatment attributes associated with the traffic flows. These attributes may comprise, for example, quality of service and/or charging attributes.
Some features associated with a service flow may need to be controlled by the gateway. Gateway may need to apply control to a traffic flow when setting up a data bearer. Control may also need to be applied to a traffic flow on an already established data bearer. The control is based on so called policy. In brief, a policy can be seen as a set of rules how the traffic flow shall be controlled.
Differences in the type of the access networks may cause problems in certain situations. A problem may be caused by the lack of information regarding the access network at the gateway. This may make it impossible for the gateway to appropriately provide control of traffic flows between the different networks it interfaces. A particular problem relates to service specific control of features such as Quality of Service (QoS), security, charging, access control and so on.